Established CO2 capture technologies such as absorption with amine solvents are associated with significant energetic and economic penalties, reducing power plant efficiency by around 10% points and increasing the cost of electricity production by up to 80%. Partly as a consequence of these limitations, deployment of large-scale carbon capture and storage (CCS) on coal power plants has been limited, and remains largely confined to regions with a particularly favourable economic and legislative environment. Dedicated research programmes worldwide have therefore pursued the development of a wide range of innovative, alternative technologies for CO2 capture, largely by addressing the fundamental gas separation step at the heart of post combustion, pre-combustion or oxyfuel combustion processes. Novel solvents with lower energy requirements than conventional amines, using phase change systems, ionic liquids, enzyme-activation, or non-aqueous solvents, are promising approaches for post-combustion capture. Alternatively, techniques used in other commercial gas separations, including solid sorbents, membranes, and cryogenic separation, have also been developed for carbon capture through extensive materials research and process optimisation. Whilst challenging for post combustion capture applications, these techniques may be of particular benefit to pre combustion capture systems where much higher partial pressures of CO2 are available, and integration of the CO2 capture step and water gas shift reaction can be achieved using sorbents or membranes. In oxyfuel combustion, membranes are also an option for efficient oxygen production, but pressurised combustion systems have demonstrated the most potential for efficiency improvements, potentially in combination with novel power cycles which are better suited to exploiting the altered combustion conditions. Finally, chemical looping combustion is a unique approach to carbon capture which can achieve dramatic energy savings through its inherent avoidance of any gas separation step, and is undergoing significant scale up. This report will review these developments in novel capture technologies and highlight the most promising strategies for achieving major cost reductions.
Title: Next-generation carbon capture technologies for coal, CCC/265
Author(s): Toby Lockwood
Publication Date: 01/05/2016